Apparatus for production of reinforced concrete precast units



H, HALLr-:R ETAL APPARATUS FOR PRODUCTION OF NEINNOROED CONCRETE PREcAsT UNITS' 3 Sheets-Sheet J;

Filed Nov. 8, 1966 mmv .Ia-n.. 27, 1979 "H HALLER v ETAL APPARATUS Foa PRonucTIoN oF REINFORCED CONCRETE PREcAsT UNITS' Filed Nov. s, 196s 3 Sheets-Sheet 2,

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H. HALLER Jai.. 27, 1970 ET AL APPARATUS FOR PRODUCTION OF REINFORCED CONCRETE PRECAST UNIISA 5 Sheets-Sheet 3 Filed Nov. 8. 1966 llgm .v @I

United States Patent O f 3,491,417 APPARATUS FOR PRODUCTION OF REINFORCED CONCRETE PRECAST UNITS Hans Haller and Erwin Wendl, both of Nibelungen 40, Graz, Austria Filed Nov. 8, 1966, Ser. No. 592,832 `Claims priority, application Austria, Nov. 12, 1965, A 10,229/ 65 Int. Cl. B28b 7/26 U.S. Cl. 25-41 3 Claims ABSTRACT F THE DISCLOSURE An assembly for the production of reinforced concrete precast units comprising a plurality of transportable moulds which can be joined in superposed and side-byside relationship, and sealing means to make the joints steam tight.

This invention relates to a proces for the production of reinforced concrete precast units, especially floor joists, by putting reinforcing steel and concrete into provided moulds, followed by a steam curing process; and to a method of production of oors, achieved by joining the aforementioned precast lloor joists longitudinally and latitudinally.

The shortage of labour in the building trade has necessitated, to an ever increasing extent, the production of prefabricatedunits and their assembly on the 'building site. The prefabrication of walls, rooting and floor slabs in factories is well known. The production often takes place at ground level or in moulds, which can be used several times. Recently a so called steam curing method has been e-mployed to accelerate the curing process. This steam curing method is valuable, because it speeds up the process of hardening the concrete, which enables the moulds to be used again very quickly. Reinforced concrete units can be produced in this way and be ready for transport in one day.

A factory-type production is only economical where there is building going on within a reasonable distance so as to exploit the capacity of such a factory to the full. The disadvantage of this factory-type production of large building units is their considerable Weight. Special vehicles are necessary for their transport from the factory to the building site, which, together with the very expensive machinery necessary for their production, very rarely makes this an economical way of building.

On the other hand larger reinforced concrete units are produced on the building site. This is done by putting up conventional shuttering (mostly timber shuttering) into which reinforcing steel and concrete are put, Where they remain until the end of the normal curing period. Expedient multiple usage of this shuttering can only rarely be made owing to the length of the curing time.

The present invention aims at removing these disadvantages by setting up transportable moulds and steam generating equipment in close proximity to the building site crane.

The production of the said reinforced concrete units, rapid curing through the introduction of steam thereto, re-moval of units from moulds and the laying of them, are all carried out on the site.

An object of the present invention is to provide apparatus for the production of reinforced concrete precast units comprising a plurality of transportable moulds for the reception of reinforcement and concrete and for the subsequent steam curing of the concrete therein, said moulds being connectable vertically and horizontally in substantially steamtight engagement.

Patented Jan. 27, 1970 According to this proposal the advantages of the steam curing method are exploited on the building site through constant re-use of the sturdily built moulds and the rapid curing of the concrete. By setting up the moulds in close proximity to the building site crane additional vehicles and transport costs from factory to site, entailed by the use of prefabricated units, are therefore eliminated.

Naturally the weight of all precast units, moulds, steam generating equipment and all accesories has to be such that any crane on a larger building site is capable of lifting and'resetting these parts. This process can, therefore, be employed on substantially all sites which have a crane, no matter how far one site is situated from the other, and has the advantage of a speedy, factory-type production without disturbing transport problems.

A central factory-type production of units for several sites has its use, even though a crane may be available, if the site suffers from a lack of space, which would render setting up of the equipment impossible, or if, because of the small size of the job, the cost of setting up and dismantling would be a considerable proportion of the total building costs. To achieve the best possible results from the plant a cycle method is recommended, which is made possible by providing several moulds and sets of moulds. In particular it will be realised that one set of moulds consists of several moulds and that several sets must be available. With this cycle method one can pour concrete in the first set, put the steel reinforcement into the second, and, if necessary, blow steam into the third. This method ensures that workers do one and the same job all the time, and provides for complete utilisation of the steam generating plant. The repetition of the same job makes the use of even unskilled labour possible. u

It is proposed to make use of multipart moulds and several sets of moulds in this process. The dimensions of each mould rnust be such that no special trai-lic license is necessary and that it can be lifted by a normal building site crane. To produce precast units of a certain pre-determined length, moulds of standard length have to be joined one behind the other, i.e. end to end in such number that an integral multiple of the length of the precast standard unit can be produced in one assembled set of moulds.

Provision is also made for the stacking and the sideways and forward movements of these sets (consisting of several moulds). The precast units are produced in this way: After concreting the first set, the second set, with its steel reinforcement is positioned on top of it. This stacking of sets can be done as often as the dimensions of the precast units will allow. The uppermost set will be closed Ly one or several steamtight lids. The fact that the sets and lids are watertight and heat insulated guarantees the least possible loss of heat during the steam blowing process on the one hand, and the greatest possible economy of the steam curing method on the other.

To achieve correct temperature, it is necessary to use a material for the moulds that has, on the one hand, a very good heat conductivity, and, on the other, very little heat capacity. Such a material facilitates also the remo-val of the concrete units by virtue of its rapid cooling (when sprayed with water, for instance) and the associated contraction of the moulds.

Small gantry cranes or lifting devices are provided to move the empty sets of moulds. The removal of the steam cured precast units from the moulds and their transport to a storage position has to be carried out by the building site crane or some other lifting device. The curing of a reinforced precast unit by means of the steam curing method takes about 13 to 15 hours. As a normal shift is 10 to 11 hours the production, curing process and the removal of the precast units from their moulds work on a 2li-hour cycle. This means that each mould and each set can be used again the following day. The removal of forms is easily done by placing the empty set of moulds next to or behind the still iilled ones where it can already be prepared for the production of the next units.

To avoid unnecessary loss of heat and steam during curing the upper and lower chords of the side walls of the sets are made of U-sections which are open at the top. The frontal and lateral areas of the lower U-section are equipped with a web plate. Complete steam tightness is achieved by putting proofing material such as sand or foam substance, into the upper U-section of each set. The projection steel plate at the bottom of the set above will then be inserted into the open U-section of the set underneath. To avoid failures in the production of precast units, constant observation of the temperature of all units is essential. For this purpose there are openings in the sets, which will allow tele-thermometers to be inserted to check the temperature in particular parts of the concrete and air chambers'inside the moulds, which can be read off on a remote indicating instrument. To enable regulation of temperature a slide-type regulator battery is provided between the steam generator and the set of moulds. This battery works in such a way that the supply of steam through each of the supply pipes into the moulds can either be decreased, increased or turned off. Further development of this method may lead to a coupling ofthe remote heat indicator with the regulator whereby it would be possible to regulate the supply of steam automatically.

CIK

As precast units suffer distortion after laying, due to their own weight and additional work load, it is essential to take these distortions into account during production. This is done by giving the individual mould a constant curvature. By virtue of this curvature the curvature of the whole set of moulds, being independent from the number of individual moulds put together, remains constant. The curvature of the set of moulds has to be chosen in such a way that the expected sag under full load is in accordance with the curvature of the set of moulds. The sag of the precast unit depends on the span, the load, the modulus of elasticity and the moment of inertia. Of these span, load and moment of inertia are fixed data. It is therefore possible to vary the sag n the stress free state when precasting despite the constant curvature through the choice of the moment of inertia by providing linings. Furthermore it is possible through the choice of rigidity of the moulds and the choice of the substructure of the bottom mould to alter the radius of the cur-vature itself.

Other objects and advantages of the invention will be hereinafter described or will become apparent to those skilled in the art and the novel features of the invention will be defined in the appended claims.

In the accompanying drawings:

FIGURE la is a plan view of a plant with two moulds lying side by side and a steam generating plant;

FIGURE 1b is a plan view of the moulds shown in FIGURE la with the cover plates removed;

FIGURE 1c is an elevation of the plant shown in FIG- URE la.'

FIGURE 2 is an end view of a mould, partly in section FIGURES 3a and 3b show details of the devices of FIG. 2 on a larger scale;

FIGURE 4 shows, in perspective, one variation of precast units laid side by side with occasional strutting, viewed from below; and

FIGURE 5 shows a cross section through the precast unit of FIGURE 4 in the vicinity of the strutting.

In these examples the manufacture of only one type of precast unit is illustrated. Naturally other types of units can be manufactured analogously.

FIGURES la, lb and 1c give a general view of the plant with three stacks of moulds side by side and three layers of moulds one upon the other, in which curing, removal and preparation for the next steam curing process is carried out in a cycle. The sets of moulds are erected side by side between crane rails 27 on which run gantry cranes 8. As can also be seen each stack of moulds consists of several layers of moulds 2, 2 and 2. In each set of moulds several units can be manufactured con currently side by side. Several moulds 17 are put together side by side, between which there are partition walls 18 and 19.

In FIGURE 2, a partition wall 19 is shown in layer 2', which is connected permanently with each mould and cannot be removed from the set, To facilitate removal of the units after curing, this partition wall 19 has an edge which tapers upwards. In layer 2 a variation of a partition wall 18 is shown which can be inserted into the set and removed from it. This partition wall 18 tapers downwards to facilitate its removal from the set. The removal of the partition wall 18 leaves a space between the units which facilitates their removal from the mould.

Steam pipes 20 are placed under the moulds. The steam is blown in through holes in the pipes 20 and heats the under side of the moulds of the layer above 2 and, at the same time, the surface of the reinforced precast units in layer 2 underneath, which also receives humidity. It is necessary to use top lids 9 which are also equipped with steam pipes to heat and humidify the surface of the units of the topmost layer 2".

FIGURES 3a and 3b show in -detail how to stack the individual moulds quickly and simply one on top of the other so that they are steamtight. The upper or lower edge has a projection 16 which projects into insulating material 15 when the molds are placed one on top of the other, thereby achieving a steamtig'ht joint.

Further measures are not necessary as the weight of the molds guarantees a steamtight joint. Between the side walls 34 of the moulds, omitted from FIG. 2 for the sake of clarity, one can put insulating material 35.

To complete the assembly, the joined moulds are provided with a stop plate 28 at either end which has openings for the steam pipes 20. The stop plates have couplings to which the steam hoses 5 of the generating plant can be connected. So that the partition walls 18 t at each joint they are provided with an aperture 11, into which a tie bar 12 is inserted to achieve a precise iit. The moulds can be joined by means of the customary connection devices 13 on the bars 12. Heating and steam production is done by a steam generator 4 with a steam distributor 10. The steam generator 4 is transportable in order to facilitate its erection and installation anywhere.

In order to start production crane rails 27, steam generator 4, steam distributor 10 and the cranes 8 are erected. At the same time moulds 3 are screwed together in layers 2 in a preparation yard. They are fitted with their stop plates 28 at either end to which the steam hoses 5 are connected at the couplings 6. After concreting the precast units, stacking of the layers of moulds and placing the top lid or cover 9 the steam curing process can begin after a certain time. The removal of the precast units is done in the following way:

After the curing of the rst layer the steam supply 5 is disconnected from this mould, the top lid 9 is removed by means of the gantry cranes, the partition walls 18 removed and the cured and finished concrete joists taken from the top layer of moulds. The joists can either be laid immediately or stacked. After removal of the precast units from the top layer of moulds, the latter is lifted off and taken to a storage area. Then the next layer of moulds is emptied and placed on the previously emptied top layer, etc. After all moulds are emptied the steel reinforcement is put in, concrete is poured, the moulds are stacked again and the top lid put on. The assembly is then ready again for the next curing process.

FIGURE 4 shows, from below, as an example, a few precast units 7 placed side by side. Each unit consists of a web 21 and two anges 22. (The Walls of the unit are so thin that the reinforcing steel is barely, but completely embedded in the concrete.) The joists are therefore so light that they can easily be moved by any normal building site crane. In case strutting is necessary for the joining of the precast units, each unit 7 has openings 23 in the web 21 and also openings 24 in the flanges. Into these openings 24 reinforcnig steel 32 can be inserted, which is particularly visible on the joist on the right of FIGURE 4. This reinforcing steel serves to reinforce the strutting 25 which can go right through al1 the joists, and connects the individual units in a very simple way.

FIGURE 5 shows how the shuttering 33 for the strutting 25 is attached without props. The shuttering 33 is attached by means of loops to a holding hook which spans the opening 23. The concrete is poured inl through the opening 23 in the precast units, and the shuttering 33 can be removed after curing and used again.

With this process it is possible to standardize the manufacture of precast units, for oors in particular, and to get the maximum benefit from prefabrication. Naturally this process allows for numerous variations. Different moulds and different units can be made and used, the number of sets of moulds lying on top of one another or side by side can be varied and the construction of moulds can be suited to the diiferent requirements.

While specific structural details have been shown and described, it should be understood that changes and alterations may be resorted to without departing from the spirit of the invention.

We claim:

1. In an apparatus for making elongated elements of cast concrete, in combination:

(a) a plurality of substantially uniform elongated mold members,

(1) each mold member having open longitudinal ends horizontally spaced in the normal operating position of said mold member and an open top; (b) first securing means for securing each mold to another mold in end-to-end relationship; y

(c) second securing means for securing each mold to another mold in side-by-side relationship, whereby said molds may be assembled in layers;

(d) third securing means for securing each of said layers to another layer of said assembled molds in superposed relationship in which each mold of one layer forms a stack with a corresponding superposed mold of another layer,

(1) said third securing means including sealing means for sealing said layers to each other,

(2) the underside of each superimposed mold dening an open space with the open top of a mold in said one layer;

(3) said secured layers of molds jointly constituting an assembly of molds, each set of molds secured in end-to-end relationship having two exposed open ends and the molds in the uppermosst layer having exposed open tops;

(e) stopping means for closing said exposed open ends; A

(f) top lid means for closing said exposed open tops;

(g) Steam generating means; and

(h) connecting means for connecting said steam gen erating means with each of said open spaces for admission of steam to said spaces.

2. In an apparatus as set forth in claim 1, said connecting means including coupling members on said stopping means adjacent said open ends.

3. In an apparatus as set forth in claim 2, said sealing means including a projection coupling and a recess on each mold, the projection on a first mold sealingly engaging the recess in a second mold when said first and second molds are superposed.

References Cited UNITED STATES PATENTS 942,092 12/1909 May 249-121 X 1,276,264 8/1918 Porter et al. 249-119 X 1,312,631 8/1919 Hellstrom 249-163 X 1,389,722 9/1921 Webb 249-126 X 1,925,733 9/1933 Pandolfi 249-119 2,239,195 4/ 1941 Henderson 249-79 X 2,499,532 3/1950 Shearer 249-126 X 2,632,225 3/1953 Miller 249-127 X 2,661,496 12/1953 Lubenow 18-6 X 2,886,876 5/1959 Wilson.

2,983,983 5/1961 Mayer 249-168 X J. SPENCER OVERHOLSER, Primary Examiner JOHN S. BROWN, Assistant Examiner Us. c1. XR. 25-119; 249-50, 126 

